The present invention relates to an image processing apparatus that performs an image process for an input color image, for example, in a digital color copying machine that reads a color image on an original and forms a copy image thereof.
Conventionally, copying machines with a single function of copying have been predominant. However, with recent development of digital technology, MFPs (Multi-Function Peripherals) with multiple functions, such as a copying function, a scanning function and a printing function, have increasingly been manufactured and marketed.
A method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-69164 is a senior invention of the inventor of the present invention, which relates to a digital color copying machine. In the senior invention, an image is fixed-length compressed in units of a block, thereby realizing an editing function such as a rotational process function at low cost. In addition, the fixed-length compressed data is then variable-length compressed, and the variable-length compressed data is stored in a hard disk drive (HDD), thus realizing electronic sorting.
The senior invention, however, is silent on how to compress data in the scan, print and copy modes in an MFP.
In the MFP, the number of colors represented by image signals and the use thereof are different in the respective processes of scanning, printing and copying. If different compression techniques are applied to the respective processes, the cost rises due to provision of a plurality of compression means and the productivity lowers due to mutual conversion of compressed data. The difference in compression technique results in such a problem that the data used in the copying and scanning processes, which use input images from the same device, cannot equally be handled for display, management, etc.
Furthermore, as regards the MFP configuration, it is difficult to increase the system extensibility at low cost, by connecting not only units for color scan and color print or units for black-and-white scan and black-and-white print, but also units for color scan and black-and-white print, or the like, wherein the number of signals in devices is different.